Internal combustion engines burn a hydrocarbon-based fuel or another combustible fuel source to convert the potential or chemical energy therein to mechanical power that can be utilized for other work. The combustion of fuel produces byproducts and emissions that the U.S. Government and other governments regulate. To comply with these regulations, engine manufacturers have developed a number of methods for reducing or treating the emissions created by the internal combustion process. One such method is exhaust gas recirculation (EGR) in which a portion of the exhaust gasses produced by the combustion process are recirculated and intermixed with the incoming intake air. The EGR process deters creation of nitrogen oxides such as NO and NO2, commonly referred to as NOX, during combustion. Because the exhaust gasses are typically still hot after their initial combustion, the EGR system often cools the emissions prior to recirculation to avoid disrupting the combustion process or to gain additional performance advantages.
Heat exchangers are devices that transfer thermal energy from one medium to another. For example, a process fluid may pass through a heat exchanger and transfer its thermal energy to a coolant before being returned to the process. An EGR system may utilize one or more heat exchangers to cool the hot exhaust gasses before returning them to the combustion process. One problem that may arise with heat exchangers, though, is the introduction and distribution of the two mediums, i.e., process fluids and coolant, within the heat exchanger. The two fluids must flow proximate to each other in order to adequately exchange thermal energy but must remain separated to avoid leakage. If the interface between the process fluid and coolant is poorly designed, efficiency of the thermal exchange may be undesirably low and leaks may occur.
Japanese Patent Publication 200900131285912 (JP '912), entitled “Cooling Water Inlet Structure of Heat Exchanger for EGR Cooler,” purports to address the problem of poor coolant distribution. The JP '912 publication describes a heat exchanger having at least two coolant inlets along one side of the heat exchanger. The design of the JP '912 publication, however, may still produce a less-than-uniform coolant distribution in the heat exchanger and therefore thermal efficiency may still be less than optimum. Accordingly, there is a need for an improved heat exchanger.